libstdc++-v3/testsuite/23_containers/span/explicit.cc

   1 // Copyright (C) 2020-2025 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do compile { target c++20 } }
  19
  20 #include <span>
  21
  22 struct Range
  23 {
  24   int* begin();
  25   int* end();
  26   unsigned size() const;
  27 } r;
  28
  29 auto first = std::begin(r), last = std::end(r);
  30
  31 // span(It, size_type)
  32 std::span<int> s1 = {first, 2};
  33 std::span<int, 2> s2 = {first, 2}; // { dg-error "explicit constructor" }
  34
  35 // span(It, End)
  36 std::span<int> s3 = {first, last};
  37 std::span<int, 2> s4 = {first, last}; // { dg-error "explicit constructor" }
  38
  39 // span(R&&)
  40 std::span<int> s5 = r;
  41 std::span<int, 2> s6 = r; // { dg-error "conversion from" }
  42
  43 // span(const span<OtherElement, OtherExtent>&)
  44 std::span<const int> s7 = s5;
  45 std::span<const int> s8 = s6;
  46 std::span<const int, 1> s9 = s5.first(1);  // { dg-error "conversion from" }
  47 std::span<const int, 1> s10 = s7.first(1); // { dg-error "conversion from" }